Posted by Larry Hoover on February 10, 2003, at 10:24:47
In reply to Thanks Larry » Larry Hoover, posted by bluedog on February 10, 2003, at 4:53:17
> Pharmacology is not my strongest point.
>
> The human body is an amazingly adaptive organism!!!
>
> regards
> bluedogYou're welcome, BD. Just so you can put this into context, other substances do not follow this half-life concept. For example, ethanol is considered to be a zeroth-order drug. It's eliminated at a constant rate, without regard to the initial concentration. If intake exceeds breakdown, you get drunker. If the converse, you get more sober. Acetylsalicylic acid (aspirin) is another zeroth-order drug. That's why the only "cure" for alcohol or aspirin overdose is time (or dialysis).
Most pharmaceuticals are first-order, obeying the logarithmic half-life rule. Yet other drugs are second-order, with yet another type of half-life decay, which *is* concentration dependent. For these, the half-life increases as the concentration decreases. In other words, it takes less time for the concentration to fall by the first half than it does for the concentration to fall by the next quarter (2nd half-life).
Please don't be surprised that this is all a very confusing subject.
Lar
poster:Larry Hoover
thread:139500
URL: http://www.dr-bob.org/babble/20030208/msgs/140421.html